系列文章目录
第一篇 spring源码解析之扩展原理BeanFactoryPostProcessor和BeanDefinitionPostProcessor和ApplicationListener
第二篇 spring bean的实例化过程
第三篇 spring容器创建准备的前期工作源码分析
第四篇 spring ioc源码解析之解决循环依赖
第五篇 spring aop源码分析之代理对象的创建
spring aop源码分析之代理对象的创建
什么是AOP
面向切面编程，相较于面向对象编程允许开发者定义纵向的关系。
AOP定义横向的关系。例如日志功能。日志代码往往横向地散布在所有对象层次中，而与它对应的对象的核心功能毫无关系。 还有权限认证、事务等。
AOP利用一种称为"横切"的技术，剖解开封装的对象内部，并将那些影响了多个类的公共行为封装到一个可重用模块，并将其命名 为"Aspect"，即切面。
切面就是那些与业务无关，却被业务模块所调用的逻辑封装起来，便于减少系统的重复代码，降低模块之间的耦合度，并有利于未来的可操作性和可维护性。
基本概念
- 横切关注点(对哪些方法进行切入) 对哪些方法进行拦截，拦截后怎么处理，这些关注点称之为横切关注点
- 切面（aspect,把原来糅杂在业务逻辑代码中的非业务代码抽取出来，把功能 相同的放在一个类中形成一个切面） 类是对物体特征的抽象，切面就是对横切关注点的抽象
- 连接点（joinpoint）（需要切入的点） 被拦截到的点，因为Spring只支持方法类型的连接点，所以在Spring中连接点指的就是被拦截到的方法，实际上连接点还可以是字段或者构造器
- 切入点（pointcut） 对连接点进行拦截的定义
- 通知（advice）
所谓通知指的就是指拦截到连接点之后要执行的代码，通知分为前置、后置、异常、返回、环绕通知五类。通知的优先顺序：环绕通知(前)->前置通知->目标方法->环绕通知（后）->后置通知->返回通知/异常通知 - 目标对象 代理的目标对象
- 织入（weave） 将切面应用到目标对象并导致代理对象创建的过程
案例
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>4.3.20.RELEASE</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.8.13</version>
<scope>compile</scope>
</dependency>
package com.yemuxia.aop01;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
@EnableAspectJAutoProxy
@Configuration
@ComponentScan(basePackages = "com.yemuxia.aop01")
public class AppConfig {
}
package com.yemuxia.aop01;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
import org.springframework.stereotype.Component;
/**
* 切面类
*/
@Component
@Aspect
public class PersonAspect {
@Pointcut("execution(* com.yemuxia.aop01.AsianPerson.*(..))")
public void pointCut(){}
@Before(value = "pointCut()")
public void myBefort(JoinPoint joinPoint) {
System.out.println("前置通知>>>>>>>>>joinPoint: " + joinPoint.getSignature().getName());
}
@After(value = "pointCut()")
public void myAfter(JoinPoint joinPoint) {
System.out.println("后置通知>>>>>>>>>joinPoint: " + joinPoint.getSignature().getName());
}
@AfterReturning(value = "pointCut()",returning = "result")
public void myAfterReturning(JoinPoint joinPoint, Object result) {
System.out.println("返回通知>>>>>>>>>joinPoint: " + joinPoint.getSignature().getName());
}
@Around(value = "pointCut()")
public Object myAround(ProceedingJoinPoint joinPoint) throws Throwable {
System.out.println("环绕通知（目标方法执行前）>>>>>>>>>joinPoint: " + joinPoint.getSignature().getName());
Object obj = joinPoint.proceed();
System.out.println("环绕通知（目标方法执行后）>>>>>>>>>joinPoint: " + joinPoint.getSignature().getName());
return obj;
}
@AfterThrowing(value = "pointCut()")
public void myThrowint(JoinPoint joinPoint) {
System.out.println("异常通知>>>>>>>>>joinPoint: " + joinPoint.getSignature().getName());
}
}
package com.yemuxia.aop01;
/**
* 被代理类接口
*/
public interface Person {
void add(int num);
}
package com.yemuxia.aop01;
import org.springframework.stereotype.Component;
/**
* 被代理类
*/
@Component
public class AsianPerson implements Person {
@Override
public void add(int num) {
System.out.println("目标方法执行");
}
}
package com.yemuxia.aop01;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class MainClass {
public static void main(String[] args) {
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);
Person person = ctx.getBean(Person.class);
person.add(2);
}
}
package com.yemuxia.aop01;
import org.springframework.stereotype.Component;
/**
* 被代理类
*/
@Component
public class AsianPerson implements Person {
@Override
public void add(int num) {
int a = 5/0;
System.out.println("目标方法执行");
}
}
从@EnableAspectJAutoProxy注解分析
我们发现@EnableAspectJAutoProxy上标注了一个@Import注解，通过前面的学习我们知道 @Import可以给我们容器中添加组件AspectJAutoProxyRegistrar
AspectJAutoProxyRegistrar的作用
实现了ImportBeanDefinitionRegistrar可以给我们容器中添加bean定义信息
往容器中注册了一个名称叫org.springframework.aop.config.internalAutoProxyCreator 类型为AnnotationAwareAspectJAutoProxyCreator 注解的apsectj自动代理创建器
public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) {
return registerOrEscalateApcAsRequired(AnnotationAwareAspectJAutoProxyCreator.class, registry, source);
}
private static BeanDefinition registerOrEscalateApcAsRequired(Class<?> cls, BeanDefinitionRegistry registry, Object source) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
//判断容器中有没有org.springframework.aop.config.internalAutoProxyCreator 名称的bean定义
if (registry.containsBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME)) {
BeanDefinition apcDefinition = registry.getBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME);
if (!cls.getName().equals(apcDefinition.getBeanClassName())) {
int currentPriority = findPriorityForClass(apcDefinition.getBeanClassName());
int requiredPriority = findPriorityForClass(cls);
if (currentPriority < requiredPriority) {
apcDefinition.setBeanClassName(cls.getName());
}
}
return null;
}
//容器中没有 那么就注册一个名称叫org.springframework.aop.config.internalAutoProxyCreator 类型是AnnotationAwareAspectJAutoProxyCreator的bean定义
RootBeanDefinition beanDefinition = new RootBeanDefinition(cls);
beanDefinition.setSource(source);
beanDefinition.getPropertyValues().add("order", Ordered.HIGHEST_PRECEDENCE);
beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
registry.registerBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME, beanDefinition);
return beanDefinition;
}
分析一下AnnotationAwareAspectJAutoProxyCreator
1>AnnotationAwareAspectJAutoProxyCreator 有实现了XXXAware接口的特性 (BeanFactoryAware)
2>还发现了AnnotationAwareAspectJAutoProxyCreator 实现了BeanPostProcessor接口（后置处理器的特性）
3>还发现了AnnotationAwareAspectJAutoProxyCreator 实现了InstantiationAwareBeanPostProcessor接口(后置处理器的一种,在实例化之前进行调用)
分析AnnotationAwareAspectJAutoProxyCreator 实现了BeanFactoryAware接口做了什么工作?
AbstractAdvisorAutoProxyCreator
@Override
public void setBeanFactory(BeanFactory beanFactory) {
//调用父类AbstractAutoProxyCreator.setBeanFactory()方法
super.setBeanFactory(beanFactory);
if (!(beanFactory instanceof ConfigurableListableBeanFactory)) {
throw new IllegalArgumentException(
"AdvisorAutoProxyCreator requires a ConfigurableListableBeanFactory: " + beanFactory);
}
//初始化bean工程
initBeanFactory((ConfigurableListableBeanFactory) beanFactory);
}
AnnotationAwareAspectJAutoProxyCreator#initBeanFactory覆盖了 AbstractAdvisorAutoProxyCreator.initBeanFactory()方法
@Override
//创建一个aop的增强器通过@Apsectj注解的方式.
protected void initBeanFactory(ConfigurableListableBeanFactory beanFactory) {
//调用父类的
super.initBeanFactory(beanFactory);
//若 apsectj的增强器工厂对象为空,我们就创建一个ReflectiveAspectJAdvisorFactory
if (this.aspectJAdvisorFactory == null) {
this.aspectJAdvisorFactory = new ReflectiveAspectJAdvisorFactory(beanFactory);
}
//不为空 我们就把aspectJAdvisorFactory 包装为BeanFactoryAspectJAdvisorsBuilderAdapter
this.aspectJAdvisorsBuilder =
new BeanFactoryAspectJAdvisorsBuilderAdapter(beanFactory, this.aspectJAdvisorFactory);
}
综上：
1:把Beanfactory 保存到AnnotationAwareAspectJAutoProxyCreator 组件上.
2: 为AnnotationAwareAspectJAutoProxyCreator 的aspectJAdvisorsBuilder aspect增强器构建器赋值
AnnotationAwareAspectJAutoProxyCreator 实现了BeanPostProcessor接口
postProcessBeforeInitialization bean对象初始化之前
postProcessAfterInitialization bean对象初始化之后
org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator实现了这个接口的这两个方法。
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) {
return bean;
}
/**
* Create a proxy with the configured interceptors if the bean is
* identified as one to proxy by the subclass.
* @see #getAdvicesAndAdvisorsForBean
*/
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if (bean != null) {
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (!this.earlyProxyReferences.contains(cacheKey)) {
//包装bean 真正的创建代理对象逻辑
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}
AnnotationAwareAspectJAutoProxyCreator 实现了InstantiationAwareBeanPostProcessor接口
后置处理器的一种,在实例化之前进行调用
@Override
public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
Object cacheKey = getCacheKey(beanClass, beanName);
// 判断TargetSource缓存中是否包含当前bean，如果不包含，则判断当前bean是否是已经被代理的bean，
// 如果代理过，则不对当前传入的bean进行处理，如果没代理过，则判断当前bean是否为系统bean，或者是
// 切面逻辑不会包含的bean，如果是，则将当前bean缓存到advisedBeans中，否则继续往下执行。
// 经过这一步的处理之后，只有在TargetSource中没有进行缓存，并且应该被切面逻辑环绕，但是目前还未
// 生成代理对象的bean才会通过此方法。
if (beanName == null || !this.targetSourcedBeans.contains(beanName)) {
if (this.advisedBeans.containsKey(cacheKey)) {
return null;
}
//若是基础的class ||或者是否应该跳过 shouldSkip直接返回false
if (isInfrastructureClass(beanClass) || shouldSkip(beanClass, beanName)) {
//把cacheKey 存放在advisedBeans中
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return null;
}
}
// Create proxy here if we have a custom TargetSource.
// Suppresses unnecessary default instantiation of the target bean:
// The TargetSource will handle target instances in a custom fashion.
// 获取封装当前bean的TargetSource对象，如果不存在，则直接退出当前方法，否则从TargetSource
// 中获取当前bean对象，并且判断是否需要将切面逻辑应用在当前bean上。
if (beanName != null) {
TargetSource targetSource = getCustomTargetSource(beanClass, beanName);
if (targetSource != null) {
this.targetSourcedBeans.add(beanName);
获取能够应用当前bean的切面逻辑
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(beanClass, beanName, targetSource);
获取能够应用当前bean的切面逻辑
Object proxy = createProxy(beanClass, beanName, specificInterceptors, targetSource);
this.proxyTypes.put(cacheKey, proxy.getClass());
return proxy;
}
}
return null;
}
protected boolean isInfrastructureClass(Class<?> beanClass) {
//是不是Advice PointCut Advisor AopInfrastructureBean 满足任意返回ture
boolean retVal = Advice.class.isAssignableFrom(beanClass) ||
Pointcut.class.isAssignableFrom(beanClass) ||
Advisor.class.isAssignableFrom(beanClass) ||
AopInfrastructureBean.class.isAssignableFrom(beanClass);
if (retVal && logger.isTraceEnabled()) {
logger.trace("Did not attempt to auto-proxy infrastructure class [" + beanClass.getName() + "]");
}
return retVal;
}
真正的创建代理对象从BeanPostProcessor处理器的后置方法开始
1:>org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessAfterInitialization
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if (bean != null) {
//通过传入的class 和beanName生成缓存key
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (!this.earlyProxyReferences.contains(cacheKey)) {
//若当前bean合适被包装为代理bean就进行处理
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}
2:>org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#wrapIfNecessary 有必要的 话进行包装
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
//已经被处理过的 不进行下面的处理
if (beanName != null && this.targetSourcedBeans.contains(beanName)) {
return bean;
}
//不需要被增强的直接返回
if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {
return bean;
}
//判断当前bean是不是基础类型的bean,或者指定类型的bean 不需要代理
if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
// Create proxy if we have advice.
//获取通知或者增强器
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
//获取的不为空，生成代理对象
Object proxy = createProxy(
bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
this.proxyTypes.put(cacheKey, proxy.getClass());
return proxy;
}
//加入advisedBeans集合中
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
3:>org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator#getAdvicesAndAdvisorsForBean
//找到符合条件的增强器
@Override
protected Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass, String beanName, TargetSource targetSource) {
//查找符合条件的增强器
List<Advisor> advisors = findEligibleAdvisors(beanClass, beanName);
if (advisors.isEmpty()) {
return DO_NOT_PROXY;
}
return advisors.toArray();
}
4:>org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator#findEligibleAdvisors
protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
//找到候选的增强器
List<Advisor> candidateAdvisors = findCandidateAdvisors();
//从候选的中选出能用的增强器
List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
extendAdvisors(eligibleAdvisors);
if (!eligibleAdvisors.isEmpty()) {
eligibleAdvisors = sortAdvisors(eligibleAdvisors);
}
return eligibleAdvisors;
}
@Override
protected List<Advisor> findCandidateAdvisors() {
// Add all the Spring advisors found according to superclass rules.
//调用父类获取增强器
List<Advisor> advisors = super.findCandidateAdvisors();
// Build Advisors for all AspectJ aspects in the bean factory.
//解析 @Aspect 注解，并构建通知器
advisors.addAll(this.aspectJAdvisorsBuilder.buildAspectJAdvisors());
return advisors;
}
public List<Advisor> findAdvisorBeans() {
// Determine list of advisor bean names, if not cached already.
//先从缓存中获取增强器 cachedAdvisorBeanNames是advisor的名称
String[] advisorNames = this.cachedAdvisorBeanNames;
//缓存中没有获取到
if (advisorNames == null) {
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the auto-proxy creator apply to them!
//从IOC容器中获取增强器的名称
advisorNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
this.beanFactory, Advisor.class, true, false);
//赋值给增强器缓存
this.cachedAdvisorBeanNames = advisorNames;
}
//在IOC容器中没有获取到直接返回
if (advisorNames.length == 0) {
return new ArrayList<Advisor>();
}
List<Advisor> advisors = new ArrayList<Advisor>();
//遍历所有的增强器
for (String name : advisorNames) {
if (isEligibleBean(name)) {
//忽略正在创建的增强器
if (this.beanFactory.isCurrentlyInCreation(name)) {
if (logger.isDebugEnabled()) {
logger.debug("Skipping currently created advisor '" + name + "'");
}
}
else {
try {
//通过getBean的形式创建增强器
//并且将bean 添加到advisors中
advisors.add(this.beanFactory.getBean(name, Advisor.class));
}
catch (BeanCreationException ex) {
Throwable rootCause = ex.getMostSpecificCause();
if (rootCause instanceof BeanCurrentlyInCreationException) {
BeanCreationException bce = (BeanCreationException) rootCause;
if (this.beanFactory.isCurrentlyInCreation(bce.getBeanName())) {
if (logger.isDebugEnabled()) {
logger.debug("Skipping advisor '" + name +
"' with dependency on currently created bean: " + ex.getMessage());
}
// Ignore: indicates a reference back to the bean we're trying to advise.
// We want to find advisors other than the currently created bean itself.
continue;
}
}
throw ex;
}
}
}
}
return advisors;
}
下面buildAspectJAdvisors这个方法为我们做了什么？
第一步:先从增强器缓存中获取增强器对象
判断缓存中有没有增强器对象,有，那么直接从缓存中直接获取返回出去
没有.....从容器中获取所有的beanName
遍历上一步获取所有的beanName,通过beanName获取beanType
根据beanType判断当前bean是否是一个的Aspect注解类，若不是则不做任何处理
调用advisorFactory.getAdvisors获取通知器
public List<Advisor> buildAspectJAdvisors() {
//先从缓存中获取
List<String> aspectNames = this.aspectBeanNames;
//缓存中没有获取到
if (aspectNames == null) {
synchronized (this) {
//在尝试从缓存中获取一次
aspectNames = this.aspectBeanNames;
//还是没有获取到
if (aspectNames == null) {
List<Advisor> advisors = new LinkedList<Advisor>();
aspectNames = new LinkedList<String>();
//从容器中获取所有的bean的name
String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
this.beanFactory, Object.class, true, false);
//遍历beanNames
for (String beanName : beanNames) {
if (!isEligibleBean(beanName)) {
continue;
}
// We must be careful not to instantiate beans eagerly as in this case they
// would be cached by the Spring container but would not have been weaved.
//根据beanName获取bean的类型
Class<?> beanType = this.beanFactory.getType(beanName);
if (beanType == null) {
continue;
}
//检查beanType是否包含Aspect
if (this.advisorFactory.isAspect(beanType)) {
aspectNames.add(beanName);
//创建一个Aspect类的源信息对象
AspectMetadata amd = new AspectMetadata(beanType, beanName);
if (amd.getAjType().getPerClause().getKind() == PerClauseKind.SINGLETON) {
MetadataAwareAspectInstanceFactory factory =
new BeanFactoryAspectInstanceFactory(this.beanFactory, beanName);
//从aspectj中获取通知器
List<Advisor> classAdvisors = this.advisorFactory.getAdvisors(factory);
if (this.beanFactory.isSingleton(beanName)) {
this.advisorsCache.put(beanName, classAdvisors);
}
else {
this.aspectFactoryCache.put(beanName, factory);
}
advisors.addAll(classAdvisors);
}
else {
// Per target or per this.
if (this.beanFactory.isSingleton(beanName)) {
throw new IllegalArgumentException("Bean with name '" + beanName +
"' is a singleton, but aspect instantiation model is not singleton");
}
MetadataAwareAspectInstanceFactory factory =
new PrototypeAspectInstanceFactory(this.beanFactory, beanName);
this.aspectFactoryCache.put(beanName, factory);
advisors.addAll(this.advisorFactory.getAdvisors(factory));
}
}
}
this.aspectBeanNames = aspectNames;
return advisors;
}
}
}
//返回空
if (aspectNames.isEmpty()) {
return Collections.emptyList();
}
//缓存中有增强器，我们从缓存中获取返回出去
List<Advisor> advisors = new LinkedList<Advisor>();
for (String aspectName : aspectNames) {
List<Advisor> cachedAdvisors = this.advisorsCache.get(aspectName);
if (cachedAdvisors != null) {
advisors.addAll(cachedAdvisors);
}
else {
MetadataAwareAspectInstanceFactory factory = this.aspectFactoryCache.get(aspectName);
advisors.addAll(this.advisorFactory.getAdvisors(factory));
}
}
return advisors;
}
//获取通知
@Override
public List<Advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstanceFactory) {
//获取标识了@AspectJ标志的切面类
Class<?> aspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();
//获取切面的名称
String aspectName = aspectInstanceFactory.getAspectMetadata().getAspectName();
validate(aspectClass);
// We need to wrap the MetadataAwareAspectInstanceFactory with a decorator
// so that it will only instantiate once.
MetadataAwareAspectInstanceFactory lazySingletonAspectInstanceFactory =
new LazySingletonAspectInstanceFactoryDecorator(aspectInstanceFactory);
List<Advisor> advisors = new ArrayList<Advisor>();
//获取切面类排除@PointCut标志的所有方法
for (Method method : getAdvisorMethods(aspectClass)) {
//每一个方法都调用getAdvisor方法来获取增强器
Advisor advisor = getAdvisor(method, lazySingletonAspectInstanceFactory, advisors.size(), aspectName);
if (advisor != null) {
advisors.add(advisor);
}
}
// If it's a per target aspect, emit the dummy instantiating aspect.
if (!advisors.isEmpty() && lazySingletonAspectInstanceFactory.getAspectMetadata().isLazilyInstantiated()) {
Advisor instantiationAdvisor = new SyntheticInstantiationAdvisor(lazySingletonAspectInstanceFactory);
advisors.add(0, instantiationAdvisor);
}
// Find introduction fields.
for (Field field : aspectClass.getDeclaredFields()) {
Advisor advisor = getDeclareParentsAdvisor(field);
if (advisor != null) {
advisors.add(advisor);
}
}
return advisors;
}
//通过方法获取增强器
@Override
public Advisor getAdvisor(Method candidateAdviceMethod, MetadataAwareAspectInstanceFactory aspectInstanceFactory,
int declarationOrderInAspect, String aspectName) {
validate(aspectInstanceFactory.getAspectMetadata().getAspectClass());
//获取aspectj的切点表达式
AspectJExpressionPointcut expressionPointcut = getPointcut(
candidateAdviceMethod, aspectInstanceFactory.getAspectMetadata().getAspectClass());
if (expressionPointcut == null) {
return null;
}
//创建advisor实现类
return new InstantiationModelAwarePointcutAdvisorImpl(expressionPointcut, candidateAdviceMethod,
this, aspectInstanceFactory, declarationOrderInAspect, aspectName);
}
//获取切点表达式
private AspectJExpressionPointcut getPointcut(Method candidateAdviceMethod, Class<?> candidateAspectClass) {
//获取切面注解 @Before @After。。。。。。
AspectJAnnotation<?> aspectJAnnotation =
AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
if (aspectJAnnotation == null) {
return null;
}
//获取切点表达式对象
AspectJExpressionPointcut ajexp =
new AspectJExpressionPointcut(candidateAspectClass, new String[0], new Class<?>[0]);
ajexp.setExpression(aspectJAnnotation.getPointcutExpression());
ajexp.setBeanFactory(this.beanFactory);
return ajexp;
}
//找到切面类中方法上的切面注解
protected static AspectJAnnotation<?> findAspectJAnnotationOnMethod(Method method) {
//Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class
for (Class<?> clazz : ASPECTJ_ANNOTATION_CLASSES) {
AspectJAnnotation<?> foundAnnotation = findAnnotation(method, (Class<Annotation>) clazz);
if (foundAnnotation != null) {
return foundAnnotation;
}
}
return null;
}
//把切点，候选的方法....统一处理生成一个增强器
public InstantiationModelAwarePointcutAdvisorImpl(AspectJExpressionPointcut declaredPointcut,
Method aspectJAdviceMethod, AspectJAdvisorFactory aspectJAdvisorFactory,
MetadataAwareAspectInstanceFactory aspectInstanceFactory, int declarationOrder, String aspectName) {
this.declaredPointcut = declaredPointcut;
this.declaringClass = aspectJAdviceMethod.getDeclaringClass();
this.methodName = aspectJAdviceMethod.getName();
this.parameterTypes = aspectJAdviceMethod.getParameterTypes();
this.aspectJAdviceMethod = aspectJAdviceMethod;
this.aspectJAdvisorFactory = aspectJAdvisorFactory;
this.aspectInstanceFactory = aspectInstanceFactory;
this.declarationOrder = declarationOrder;
this.aspectName = aspectName;
if (aspectInstanceFactory.getAspectMetadata().isLazilyInstantiated()) {
// Static part of the pointcut is a lazy type.
Pointcut preInstantiationPointcut = Pointcuts.union(
aspectInstanceFactory.getAspectMetadata().getPerClausePointcut(), this.declaredPointcut);
// Make it dynamic: must mutate from pre-instantiation to post-instantiation state.
// If it's not a dynamic pointcut, it may be optimized out
// by the Spring AOP infrastructure after the first evaluation.
this.pointcut = new PerTargetInstantiationModelPointcut(
this.declaredPointcut, preInstantiationPointcut, aspectInstanceFactory);
this.lazy = true;
}
else {
// A singleton aspect.
this.pointcut = this.declaredPointcut;
this.lazy = false;
//实例化切面
this.instantiatedAdvice = instantiateAdvice(this.declaredPointcut);
}
}
//获取advice 切面对象
@Override
public Advice getAdvice(Method candidateAdviceMethod, AspectJExpressionPointcut expressionPointcut,
MetadataAwareAspectInstanceFactory aspectInstanceFactory, int declarationOrder, String aspectName) {
//获取候选的切面类
Class<?> candidateAspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();
validate(candidateAspectClass);
//获取切面注解
AspectJAnnotation<?> aspectJAnnotation =
AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
if (aspectJAnnotation == null) {
return null;
}
// If we get here, we know we have an AspectJ method.
// Check that it's an AspectJ-annotated class
if (!isAspect(candidateAspectClass)) {
throw new AopConfigException("Advice must be declared inside an aspect type: " +
"Offending method '" + candidateAdviceMethod + "' in class [" +
candidateAspectClass.getName() + "]");
}
if (logger.isDebugEnabled()) {
logger.debug("Found AspectJ method: " + candidateAdviceMethod);
}
AbstractAspectJAdvice springAdvice;
//判断注解的类型
switch (aspectJAnnotation.getAnnotationType()) {
//是切点的返回null
case AtPointcut:
if (logger.isDebugEnabled()) {
logger.debug("Processing pointcut '" + candidateAdviceMethod.getName() + "'");
}
return null;
//是不是环绕通知
case AtAround:
springAdvice = new AspectJAroundAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
break;
//是不是前置通知
case AtBefore:
springAdvice = new AspectJMethodBeforeAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
break;
//是不是后置通知
case AtAfter:
springAdvice = new AspectJAfterAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
break;
//返回通知
case AtAfterReturning:
springAdvice = new AspectJAfterReturningAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
AfterReturning afterReturningAnnotation = (AfterReturning) aspectJAnnotation.getAnnotation();
if (StringUtils.hasText(afterReturningAnnotation.returning())) {
springAdvice.setReturningName(afterReturningAnnotation.returning());
}
break;
//是不是异常通知
case AtAfterThrowing:
springAdvice = new AspectJAfterThrowingAdvice(
candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
AfterThrowing afterThrowingAnnotation = (AfterThrowing) aspectJAnnotation.getAnnotation();
if (StringUtils.hasText(afterThrowingAnnotation.throwing())) {
springAdvice.setThrowingName(afterThrowingAnnotation.throwing());
}
break;
default:
throw new UnsupportedOperationException(
"Unsupported advice type on method: " + candidateAdviceMethod);
}
// Now to configure the advice...
springAdvice.setAspectName(aspectName);
springAdvice.setDeclarationOrder(declarationOrder);
/** 获取方法的参数列表名称，
比如方法 int sum(int numX, int numY),
* getParameterNames(sum) 得到 argNames = [numX, numY] */
String[] argNames = this.parameterNameDiscoverer.getParameterNames(candidateAdviceMethod);
if (argNames != null) {
//为切面设置参数
springAdvice.setArgumentNamesFromStringArray(argNames);
}
springAdvice.calculateArgumentBindings();
return springAdvice;
}
5:>org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator#findAdvisorsThatCanApply
//获取能够使用的增强器
protected List<Advisor> findAdvisorsThatCanApply(
List<Advisor> candidateAdvisors, Class<?> beanClass, String beanName) {
ProxyCreationContext.setCurrentProxiedBeanName(beanName);
try {
return AopUtils.findAdvisorsThatCanApply(candidateAdvisors, beanClass);
}
finally {
ProxyCreationContext.setCurrentProxiedBeanName(null);
}
}
//获取能使用的增强器
public static List<Advisor> findAdvisorsThatCanApply(List<Advisor> candidateAdvisors, Class<?> clazz) {
if (candidateAdvisors.isEmpty()) {
return candidateAdvisors;
}
List<Advisor> eligibleAdvisors = new LinkedList<Advisor>();
//遍历候选的增强器 把他增加到eligibleAdvisors集合中返回
for (Advisor candidate : candidateAdvisors) {
if (candidate instanceof IntroductionAdvisor && canApply(candidate, clazz)) {
eligibleAdvisors.add(candidate);
}
}
boolean hasIntroductions = !eligibleAdvisors.isEmpty();
for (Advisor candidate : candidateAdvisors) {
if (candidate instanceof IntroductionAdvisor) {
// already processed
continue;
}
if (canApply(candidate, clazz, hasIntroductions)) {
eligibleAdvisors.add(candidate);
}
}
return eligibleAdvisors;
}
//判断是当前的增强器是否能用 通过方法匹配来计算当前是否合适当前类的增强器
public static boolean canApply(Advisor advisor, Class<?> targetClass, boolean hasIntroductions) {
if (advisor instanceof IntroductionAdvisor) {
return ((IntroductionAdvisor) advisor).getClassFilter().matches(targetClass);
}
else if (advisor instanceof PointcutAdvisor) {
PointcutAdvisor pca = (PointcutAdvisor) advisor;
return canApply(pca.getPointcut(), targetClass, hasIntroductions);
}
else {
// It doesn't have a pointcut so we assume it applies.
return true;
}
}
public static boolean canApply(Pointcut pc, Class<?> targetClass, boolean hasIntroductions) {
Assert.notNull(pc, "Pointcut must not be null");
if (!pc.getClassFilter().matches(targetClass)) {
return false;
}
//创建一个方法匹配器
MethodMatcher methodMatcher = pc.getMethodMatcher();
if (methodMatcher == MethodMatcher.TRUE) {
// No need to iterate the methods if we're matching any method anyway...
return true;
}
//包装方法匹配器
IntroductionAwareMethodMatcher introductionAwareMethodMatcher = null;
if (methodMatcher instanceof IntroductionAwareMethodMatcher) {
introductionAwareMethodMatcher = (IntroductionAwareMethodMatcher) methodMatcher;
}
//获取本来和接口
Set<Class<?>> classes = new LinkedHashSet<Class<?>>(ClassUtils.getAllInterfacesForClassAsSet(targetClass));
classes.add(targetClass);
//循环classes
for (Class<?> clazz : classes) {
//获取所有的方法 进行匹配
Method[] methods = ReflectionUtils.getAllDeclaredMethods(clazz);
for (Method method : methods) {
if ((introductionAwareMethodMatcher != null &&
introductionAwareMethodMatcher.matches(method, targetClass, hasIntroductions)) ||
methodMatcher.matches(method, targetClass)) {
return true;
}
}
}
return false;
}
6:>org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#createProxy创建代理对象
protected Object createProxy(
Class<?> beanClass, String beanName, Object[] specificInterceptors, TargetSource targetSource) {
//判断容器的类型ConfigurableListableBeanFactory
if (this.beanFactory instanceof ConfigurableListableBeanFactory) {
AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);
}
//创建代理工程
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.copyFrom(this);
/** 默认配置下，或用户显式配置 proxy-target-class = "false" 时，
* 这里的 proxyFactory.isProxyTargetClass() 也为 false
*/
if (!proxyFactory.isProxyTargetClass()) {
if (shouldProxyTargetClass(beanClass, beanName)) {
proxyFactory.setProxyTargetClass(true);
}
else {
/* * 检测 beanClass 是否实现了接口，若未实现，则将 *
proxyFactory 的成员变量 proxyTargetClass 设为 true */
evaluateProxyInterfaces(beanClass, proxyFactory);
}
}
//获取容器中的方法增强器
Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
proxyFactory.addAdvisors(advisors);
proxyFactory.setTargetSource(targetSource);
customizeProxyFactory(proxyFactory);
proxyFactory.setFrozen(this.freezeProxy);
if (advisorsPreFiltered()) {
proxyFactory.setPreFiltered(true);
}
//创建代理对象
return proxyFactory.getProxy(getProxyClassLoader());
}
public Object getProxy(ClassLoader classLoader) {
return createAopProxy().getProxy(classLoader);
}
@Override
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) {
Class<?> targetClass = config.getTargetClass();
if (targetClass == null) {
throw new AopConfigException("TargetSource cannot determine target class: " +
"Either an interface or a target is required for proxy creation.");
}
//是否实现了接口
if (targetClass.isInterface() || Proxy.isProxyClass(targetClass)) {
//jdk代理
return new JdkDynamicAopProxy(config);
}
//cglib代理
return new ObjenesisCglibAopProxy(config);
}
else {
return new JdkDynamicAopProxy(config);
}
}
@Override
public Object getProxy(ClassLoader classLoader) {
if (logger.isDebugEnabled()) {
logger.debug("Creating JDK dynamic proxy: target source is " + this.advised.getTargetSource());
}
Class<?>[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised, true);
findDefinedEqualsAndHashCodeMethods(proxiedInterfaces);
//创建jdk代理对象
return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this);
}